The following are known as conventional arts for obtaining an optimum recording condition with respect to an optical recording medium such as a magneto-optical disk where information is recorded by a light beam.
As the first conventional example, Japanese Laid-Open Patent Application No. 266476/1993 (Tokukaihei 5-266476) discloses an information recording apparatus. This apparatus adopts a method for modulating a power of a semiconductor laser at a power PH of a high level and at a power PL of a low level. The relation between PH and PL is preliminarily determined (PH+.alpha.PL=uniform), and a recording power is controlled by feeding back the emitted power of the semiconductor laser.
As the second conventional example, J. Mag. Soc. Jpn., Vol. 15, Supplement No. S1 (1991) discloses a recording control method on PP 395-398. In this method, a edge position of a recording light pulse is controlled for each kind of pulses so that an optimum recording mark is recorded.
However, in the first conventional example, since a semiconductor laser can be controlled so as to have an uniform emitting power but a recording state on the recording medium is not fed back, there exists a problem that actual recording conditions including the recording medium cannot be controlled. Furthermore, in the second conventional example, since the recording mark has a teardrop shape, a reproduced waveform is different in its forward part and its backward part of the mark. Therefore, there arises a problem that accurate data cannot be reproduced.
In order to solve the two problems, a test-writing recording control method is used as the third conventional example. The test-writing recording control method is a method for temporarily recording predetermined data into the magneto-optical disk and reading the recorded data out so as to set an optimum laser power. The test-writing recording control method of the magneto-optical disk which has been disclosed in Technical Report of the Institute of Electronics, Information and Communication Engineers MR 92-62 (1991-11), PP 13-18 or Autumn Meeting Notes of IEICE C-342, PP 5-21 will be explained referring to FIG. 31.
In the above method, first, a recording mark 16 of a shortest mark repeat pattern X and a recording mark 17 of a longest mark repeat pattern Y are recorded to a magneto-optical disk. Then, the recording marks 16 and 17 are read out, and a difference in a voltage .increment.V between an average voltage V1 of a reproduced signal W which corresponds to the shortest mark repeat pattern X and an average voltage V2 of the reproduced signal W which corresponds to the longest mark repeat pattern Y is obtained.
Heat interference between the recording marks 16 and 16, the recording marks 16 and 17, the recording marks 17 and 17 or other recording marks can be almost kept uniform by carrying out the recording while the light beam power being controlled so that the difference in voltage .increment.V becomes 0. Therefore, the more accurate recording can be carried out. The heat interference is an influence given by a heat, which has been generated while recording a certain recording mark, when the next recording mark is recorded.
In addition a laser power Pw changes in proportion to a power Pas of an auxiliary light (Pw=2.times.Pas), like the first conventional example, a relationship between two power values is preliminarily determined. Moreover, the recording optical pulse is further subdivided and one recording mark is recorded as a lot of recording pulses, thereby preventing the recording mark from having a teardrop shape.
However, the above third art has a first problem that the heat interference is difficult to be accurately kept uniform.
If a length of the marks and a distant between the marks are different, the heat interference becomes different, so the mark having a prescribed size cannot be recorded.
In FIG. 31, the heat interference between the recording marks 16 and 16 of the shortest mark repeat pattern X causes a fluctuation in the level of the reproduced signal W. Since the distance between the longest marks 17 and 17 is long, the heat interference does not cause the fluctuation in the level of the reproduced signal W. Therefore, the average voltage V1 fluctuates due to the heat interference but the average voltage V2 does not fluctuate. In other words, with the arrangement of the third conventional example, it is difficult to exactly know all the heat interference from the difference in voltage .increment.V, even if the difference in voltage .increment.V becomes 0, not all the heat interference necessarily becomes uniform. Therefore, the arrangement has a first problem that the heat interference in the shortest mark repeat pattern X can be optimized but the heat interference between the other marks cannot be optimized. In other words, a reproducing duty of the shortest mark repeat pattern X becomes optimum by optimizing the heat interference in the shortest mark repeat pattern X, but the heat interference of the other marks does not become optimum.
In addition, the second problem is as follows. When the relationship between the two values of the laser power is determined, only a one-dimensional power value is adjustable. However, as an ambient temperature or the sensitivity of the recording medium changes, the relationship between the predetermined two values of the laser power (Ph+.alpha.PL=constant, or Pw=2.times.Pas) also changes. As a result, the two-dimensional power value requires adjustment. In other words, since the two values of the laser power are not independently controlled, an adjusting range is narrow and it is difficult to obtain the optimum laser power. This is not limited to the laser power values, and is also applicable to the case where the length and the width of the recording pulse (or interval or period of the pulses) is a recording variable, so there exists a problem that since the position of the edge of the recording pulse is fixed, the length and the width of the recording pulse cannot be independently controlled.
In addition, the third problem is a deterioration in reliability of the test-writing due to repetition of the test-writing. In other words, since the recording information may be destroyed by the test-writing, in order to solve this problem, it is necessary to newly provide an exclusive test-writing area for the test-writing so as to distinguish it from the information recording reproducing area. However, since the test-writing must be carried out every time when the ambient temperature changes or the sensitivity of the recording medium changes due to replacement of the recording medium, etc., it is anticipated that the number of rewriting in the test-writing area increases extremely. For example, if the test-writing is carried once in every three minutes, the rewriting is carried out approximately 10.sup.6 times in six years. It is expectable that the above number exceeds the guaranteed number of the rewriting on the recording medium, so there arises a problem that the reliability of the test-writing deteriorates.